Understanding Of Hydrogeological Conditions Research Articles

Damage Features and Formation Mechanism of the Strong Water Inrush Disaster at the Daxing Co Mine, Guangdong Province, China

The largest water disaster in the history of coal mining in China with respect to maximum water inrush quantity (≈ 13,600 m3/min) occurred at the Daxing underground mine in 2005. Triggered by accumulated water in a higher-level, mined out (goaf) area, it caused great damage, including 121 deaths and direct economic losses of over 47 million yuan. Damage to the roof and floor rock caused by mining-induced redistribution of ground stress is believed responsible for the caving of the roof and the subsequent inrush, though accumulated water in the goaf area, the weight of the roof pillar, fractures due to minor faults, the comprehensive influence of groundwater, including the pore water pressure and the water’s chemical action, and the steeply inclined coal seam all contributed to the scale of the disaster. The inrush site was located near a fault and had been observed as an anomaly during geophysical testing. Recommendations made based on this tragedy include: mining of steeply inclined coal seams beneath water bodies must be forbidden due to the lack of effective mitigation measures; the integrity of waterproof pillars must be a major priority; and underground mining requires a thorough understanding of hydrogeological conditions, which must be regularly updated through the mining process.

Ground Water Security and Drought in Africa: Linking Availability, Access, and Demand

Drought in Africa has been extensively researched, particularly from meteorological, agricultural, and food security perspectives. However, the impact of drought on water security, particularly ground water dependent rural water supplies, has received much less attention. Policy responses have concentrated on food needs, and it has often been difficult to mobilize resources for water interventions, despite evidence that access to safe water is a serious and interrelated concern. Studies carried out in Ghana, Malawi, South Africa, and Ethiopia highlight how rural livelihoods are affected by seasonal stress and longer-term drought. Declining access to food and water is a common and interrelated problem. Although ground water plays a vital role in buffering the effects of rainfall variability, water shortages and difficulties in accessing water that is available can affect domestic and productive water uses, with knock-on effects on food consumption and production. Total depletion of available ground water resources is rarely the main concern. A more common scenario is a spiral of water insecurity as shallow water sources fail, additional demands are put on remaining sources, and mechanical failures increase. These problems can be planned for within normal development programs. Water security mapping can help identify vulnerable areas, and changes to monitoring systems can ensure early detection of problems. Above all, increasing the coverage of ground water-based rural water supplies, and ensuring that the design and siting of water points is informed by an understanding of hydrogeological conditions and user demand, can significantly increase the resilience of rural communities to climate variability.

Well logging methods in groundwater surveys of complicated aquifer systems: Bohemian Cretaceous Basin

Geophysical well logging methods (including borehole flow logging) can significantly contribute to a detailed understanding of hydrogeological conditions in basins with complicated sedimentary structure in studies undertaken to make optimal use of water sources, or to protect those resources from contamination. It is a common practice to delineate geological and hydrogeologic conditions at the scale used in geological maps and surface surveys. However, there is a need for more detailed descriptions of basin structure for many tasks related to water resources management and hydrologic research. This paper presents four specific examples of boreholes in complex hydrogeologic settings where useful information was provided by geophysical logging: (1) identification of large-scale upward cross-flow between aquifer horizons in an open borehole; (2) confirmation of continuous permeability throughout a long borehole interval; (3) identification of leakage into a test well via a defective casing joint; (4) evidence for downward flow in open boreholes; and (5) identification of permeable beds associated with water inflows during aquifer tests. These borehole geophysical measurements provide important information about the detailed lithological profiles of aquifers (especially in the absence of core), enabling the optimization of groundwater monitoring, resource use, and wellhead protection activities.